I will give this a try and others can fill in where I either get it wrong or leave something out.

In general the system is pretty simple. The "shocks" in the wheel well are really nothing more than hydraulic rams that control ride height. The shock absorbing function is contained in the pressurized spheres, the source of hydraulic pressure is the pump, and the ride height regulator is a three way valve. A reservoir to provide hydraulic fluid to lift the car to the maximum height and then take back the fluid with the car at the lowest ride height is also provided. It has a strainer element in it.

The pump, with the engine running, constantly supplies the control valve mounted on the body of the car above the rear suspension, with oil pressure. The minimum pressure at idle is enough to lift the rear of the car. The valve is set mechanically using a linkage to port pressure to the struts at the wheels when the ride height (the distance from the car frame or body to one of the suspension members) is lowered by load. When the ride height is restored to the set point the valve closes the ports to the struts and goes to a position that allows recirculation leakage so the pump does not overheat. When the load is removed and ride height goes up above the set point the port to the struts is connected to the return line and the weight of the rear squeezes the extra fluid from the struts back to the reservoir until the ride height is lowered enough to reset the valve to the recirculation position.

All the ride functions, absorbing shock and damping responses, comes from the path through the spheres. It is odd when you work on the system and the spheres are bad. Changing the ride height by manipulating the valve results in instantatneous ride height changes, like those bouncing cars with hydraulic suspensions you see, usually in "low rider" mode. With the spheres intact the rate of change is very much delayed especially when the rear end is lowered.

Anyway that is about it. The gas pressurized shocks from Bilstein we are used to are duplicated in terms of shock absorbing (small bumps and the like) using a Nitrogen blanket inside the sphere. The valving and damping functions are provided in the areas of the connections to the hydraulic fluid.

That is about it. Jim

__________________
Own:
1986 Euro 190E 2.3-16 (291,000 miles),
1998 E300D TurboDiesel, 231,000 miles -purchased with 45,000,
1988 300E 5-speed 252,000 miles,
1983 240D 4-speed, purchased w/136,000, now with 222,000 miles.
2009 ML320CDI Bluetec, 89,000 miles

Owned:
1971 220D (250,000 miles plus, sold to father-in-law),
1975 240D (245,000 miles - died of body rot),
1991 350SD (176,560 miles, weakest Benz I have owned),
1999 C230 Sport (45,400 miles),
1982 240D (321,000 miles, put to sleep)